FOXO4 and neoplasm: FOXO4 has been implicated as a negative regulator of cell proliferation in several tumours, but a link to steroidogenesis has not previously been established (Liet al., 2016).GRAMD1B has been shown to be enriched in mouse fetal Leydig cells following CRHR1 agonist stimulation (McDowellet al., 2012), and has been identified in other expression studies of mouse fetal Leydig cells (Inoueet al., 2016;McClelland & Yao, 2017).